This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. A variable-density spiral k-space trajectory is introduced for brain functional magnetic resonance imaging (fMRI). The proposed spiral trajectory consists of an Archimedean spiral from the k-space origin to an arbitrary fraction r of the maximum k-space radius, extending beyond this point with a variable-density spiral in which the sampling density decreases as the k-space radius increases. It therefore permits a reduction in readout time at the expense of undersampling only the high spatial frequencies, in which the energy in T2*-weighted brain images is typically low. To read about other projects ongoing at the Lucas Center, please visit http://rsl.stanford.edu/ (Lucas Annual Report and ISMRM 2011 Abstracts)